1. Field of the Invention
The present invention relates to a photoelectric conversion element, an image reading device, and an image forming apparatus.
2. Description of the Related Art
A color complementary metal-oxide semiconductor (CMOS) linear image sensor that operates in a global shutter mode simultaneously exposes every pixel at the same instant in time and stores signals at once, and the signals are sequentially read out. In the global shutter mode, such simultaneous exposure can avoid spatial distortion that could occur in a rolling shutter mode, but each of the pixels needs an analog memory for storing the signal.
Such an analog memory and a pixel circuit including a floating diffusion that converts electric charge output from a photo diode into voltage occupy a certain area of a pixel to configure a circuit. In conventional linear image sensors, such an area occupied by the analog memory and the pixel circuit increases the gap between photo diodes in different colors, which is one of the factors that exacerbate color shift.
Japanese Unexamined Patent Application Publication No. 2015-156557 discloses a solid state imaging device including a plurality of pixels, a plurality of first charge accumulation circuits that output first pixel signals in accordance with signal charge, and a plurality of second charge accumulation circuits that output second pixel signals corresponding to signal charge that are reduced to a predetermined number of pixels.
However, such a conventional device cannot reduce color shift or prevent decrease in sensitivity.